This invention relates in general to the manufacture of cheese and, in particular, to the manufacture of cheese made by the Emmenthaler process, more commonly known in the United States as Swiss cheese.
Swiss cheese is made by a series of time honored steps which trace their origin back several hundred years to Canton Bern, in the valley of the Emme, Switzerland. This process results in a cheese characterized by a nut-like flavor and cells or eyes formed during the curing process by expanding gases generated by bacterial action within the body of the cheese. According to the usual procedure, the milk used in the manufacture of cheese is first clarified to remove sediment, disperse clusters of fat, and to increase the elasticity of the curd in the cheese, all of which contribute to improved eye formation. After the milk is clarified, it is usually desirable to standardize the milk to a uniform fat content in the range of about 2.8 percent to about 3.5 percent so that the cheese product will contain approximately 45 percent of fat in its dry matter. The milk is then placed in a kettle or vat and warmed to the proper temperature for setting, normally between 85.degree. and 95.degree. F., whereafter the milk is innoculated with a suitable culture of the type necessary to produce the characteristic nutty flavor of Swiss cheese. The cultures may include, for example, Lactobacillus bulgaricus, Streptococcus thermophillus, and Propionibacterium shermanii. Rennet is then added to coagulate the milk and to set it into a curd. "Curd" is a term of art referring to the solids portion and "whey" is a term of art referring to the remaining liquid.
As soon as the curd has attained the desired firmness, usually determined by the eye of an experienced cheese maker, it is cut into small pieces with what is known in the art as a Swiss cheese harp. The pieces of curd are then cooked at a temperature range of about 120.degree. to 130.degree. F. while being continuously stirred in the whey until the desired moisture level, firmness, and density as determined by the cheese maker is achieved.
At this point the curd is separated from the whey by a step known in the art as "dipping". This is accomplished by passing a heavy coarsely woven cloth under the curd in the vat so that the cloth may be formed into a large bag. The curd is removed from the vat and the excess whey is allowed to drain from the curd into the vat. The curd is then "hooped" by placing the cloth containing the curd in a circular hoop having a depth of 6 to 8 inches. The cloth is drawn up around the curd, and the curd is pressed into the hoop to shape it and promote whey drainage. Thereafter, the curd is kept under pressure and turned at intervals overnight so that any holes or air cavities formed in the body of the curd are removed.
The next morning, after the curd has been pressed in the hoop overnight, it is placed in a salt brine solution at a temperature of 50.degree. to 60.degree. F. for two to four days. The brine salts the exterior surface of the curd and works into the body of the curd during the curing operation. Thereafter, the curd is removed from the brine and cured by alternately storing it at cold (approximately 55.degree. F.) and warm (approximately 75.degree. F.) temperatures accompanied by repeated washings and saltings. Eye formation should commence by the time the cheese is about three weeks old. However, the curd is not considered fully cured until optimal eye formation is attained which may require a curing period of from 60 days to 6 months or longer.
It is desirable to produce Swiss cheese having eyes of uniform size and distribution throughout the body of the cheese. One attempt to produce such a Swiss cheese is disclosed in J. B. Stine, U.S. Pat. No. 3,020,163, "MANUFACTURE OF CHEESE". This patent discloses a process wherein the so-called "one-sidedness" or non-uniform eye distribution within the cheese is minimized by a rapid cooling of the curd in the whey from the cooking temperature (120.degree.-135.degree. F.) to a temperature in the range of 90.degree. to 110.degree. F. just prior to removing the curd from the whey. While this process may be successful in improving the uniformity of eye formation, the process still requires that the cheese be cured for a relatively lengthy period which necessitates storage space requirements and results in delays in marketing the final cheese product.